Need wwan gnome-settings-daemon plugin
Feature: https://source.puri.sm/Librem5/use-cases/issues/4
As discussed with @bob.ham and @andrea.schaefer at GUADED 2018 we want something in the user session that:
- brings up the modem (e.g. pops up the sim card dialog via gcr)
- allows applications via a simple API to find out if the modem is ready (and if not initiate that)
Similar code used to live in nm-applet but that's (AFAIK) not used anymore in GMOME3. This will have interactions with #38 (closed) so parts might life in g-s-d.